Speed compensating motor drive for phonograph turntables



n 0 1 B. w. CARRINGTON 2,421,911

I S REED 'COMPENSATINGMOTOR DRIVE FOR PHONOGRAPH TURNTABLES Filed Oct 24, 1945 s Sheets-She et 1 June 01 1947' B. w. CARRINGTON 2,421,911 SPEED CQMPENSATIQG MOTOR DRIVE FOR PHONOGRAPH TURNTABLES a Sheets-Sheet 3' Filed Oct. 24, 1945 mmvrox.

Patented June 10, 1947 SPEED COMPENSATING MOTOR DRIVE FOR PHONOGRAPH TURNTABLES Blake W Carrington, Elyria, Ohio, assignor to The General Industries Company, Elyria, Ohio,

a corporation of Ohio Application October 24, 1945, Serial No. 624,231

1 My invention relates to speed compensating motor drives for phonograph turntables and more particularly relates to turntable speed compensating motor drive mechanisms of the frictional driving type.

The mechanism of my present invention is of the same general type as that of my co-pending application, Ser. No. 596,749, filed May 30, 1945,

wherein a phonograph turntable is driven by a preferably electric motorand a driving roller affixed to the motor shaft through an intermediate friction idler wheel interposed between said roller and a pendant peripheral flange of the turntable. In such prior mechanism, upon the application of variable increasing loads to the turntable, the resultant reactive eifect of the load upon the idler wheel causes a translatory movement of the idler, which, in turn, reacts upon the motor roller, which with" the motor is adapted to tilt, whereby the motor roller being 30 resultantly variably tilted, the idler wheel is caused to engage a progressively difierent longitudinally disposed portion of the motor rolle which is of progressively larger diameter.

As a result of the above operation, the driving ratio as between the roller and the idler wheel being automatically responsive to varying turntable loads, not only speed reducing load effects imposed upon the motor, but also'and more importantly, slippage between the peripheral surface of the idler and the engaged surfaces of the roller and turntable flange may be effectually offset by such greater driving ratio, the relative values of which may be predetermined by making the outer surface of the roller of suitable tapered form. I

Phonograph turntables are not always provided with a pendant peripheral flange, nor with the flange of sufficient depth to accommodate the thickness of the idler wheel and the upper por;

tion of the driving roller, and many such turntables employing otherwise suitable pendant flanges do not have the inner surfaces thereof truly cylindrical and smooth and, for .these and other reasons, it is frequently more desirable to In my present invention therefore, I dispose the idler wheel in a. plane which is normal to that of the uppermost disc portion of the turntable and adapt it for engagement with such disc portion near its periphery, and, as one fur- 7 Claims. (Cl. 74-206) journalled co-axially with the turntable and adapted for turntable speed compensating trans latory lateral movements commensurable with variations in turntable load;

' 1n the herein disclosed embodiment of my present invention, the driving ratio between the motor and the turntable is properly varied, according {to the varying loads imposed upon the turn- .table, by a thrust effort exerted thereon, and tilting a properly longitudinally configured motor ,roller in such manner as to vary the zone of engagement of the idler wheel with respect to different longitudinally disposed portions of the roller, whereby a desired substantially uniform turntable speed is maintained, even though the motor speed at time is considerably reduced,

because of the reactive effect of varying loads imposed upon the turntable.

An object of my invention is to provide an improved speed regulating mechanism adaptable for use in connection with a phonograph tum- ,table or the like, which is subjected to considerable variations in load during a desired period of operation.

Another object of my invention is to achieve prompt and reliable speed regulation of a phonograph turntable or the like as a result of a reactively bodily movable idler wheel interposed between a motor driven rollerand' a planular element of the turntable.

Another object of my invention is to 'mini- ,mize slippage between the roller and idler wheel of an improved speed compensating mechanism such slippage in prior constructions having unduly increased the necessary range of compensation required. l Other objects of my invention and the invention itself will be clear to those skilled in the art to which my invention appertains from the following specificationand the accompanying drawings which are illustrative of a preferred embodiment of my invention wherein:

Fig. 1 is a plan view of an embodiment of my invention wherein only afragment of the tumtable is shown, portions thereof being broken away to expose the underlying motorand frictional drive transmission;

Fig. 2 is a view partially in side elevation and partially in section, the view being taken at the right hand side of Fig. 1;

Fig. 3 is a view similar to thatof Fig. 2 but showing the parts viewed from below the showing of Fig. 1; and a Fig. 4 is a transverse diametrical section taken.

ther feature of improvement, I preferably mount 56 on the line 4-4 of Fig. 1;

the idler wheel on a swinging support which is Fig. 5 is a side elevational view of a slideable idler wheel carrier, the view being taken from the A I line -5 of Fig. 4.

Referring now to all of the figures of drawing, each of which is illustrative of the same preferred embodiment of my invention and in each of which like parts are designated by like reference characters, at I I show'a turntable having a very short pendant peripheral flange 2 and a hub 3 having a conical axial opening 4 by which the turntable is fitted over a similarly conical surface of a turntable post 5 which is journalled, at its lower end, in a bearing support 6, said bearing support being pendantly secured to a mounting plate I in any suitable manner.

The mounting plate I not only carries the journal 6 for supporting the turntable post and turntable, but also pendantly supports a motor M by virtue of trunnions 8 and 9 which are in axial alignment at the top and bottom portions of the motor frame and which, in turn, are journalled within cylindrical sleeves In, said sleeves having upper and lower flanges, as at H, and being thereby substantially spool shaped, a, rubber cushioning grommet l2 of annular form being fitted over the cylindrical portion of each said sleeve and between its end flanges, said grommet being medially circumferentially provided with an annular groove l3 to accommodate portions of the mounting plate I and mounting plate extension 1' respectively for the upper and lower grommets, said plate and plate extension being suitably perforated for placement of the grommets in the resultant perforations.

The motor M may be of any suitable type and,

v for example, inmost cases, may well be of the asynchronous type-and, in any event, is provided with a motor shaft H which extends from one side either of the motor, as best shown in Figs. 1 and 2,'and on said shaft a tapered pulley or driving roller I5 is afllxed either by drive fitting the samethereonor by means of a set screw Hi.

The motor shaft and roller are adapted for oscillatory movement about an axis passing through the axes of the trunnions 8 and 9 and, incidentally, in most cases, passing transversely through a. portion of the motor shaft ll which is projected through the usual motor roller, not illustrated.

Such rotative oscillation of the motor is resiliently restricted by the provision of spring means such as the spring I! and the spring I8, the axis of oscillation of the motor being located as at l9, Fig. 1.

The idler wheel is journalled on a post 2| rigidly'secured in a central aperture 2| of a between a more upwardly disposed portion of said The arm 22, as best arm 22 and said carrier. shown in Fig. 1, is provided with a tubular flange 22a whereby it is rotatably journalled on the bearing support 6 for the turntable post P,

The idler wheel is always maintained inpressure engagement with the underside of the tumtable at 21 by virtue of the resilient pull exerted by the spring 25.,on the idler carrier 25 which carried the rotatable wheel 20. The details of the relationship between the slide-carried idler wheel mount and the pendant portions 22' of the swingable arm 22 are best illustrated in Fig. 5 which shows arm extensions 22' upon which the body portion 29 is slideably fitted.

By reference particularly to Figs. 1, 2 and 3,

the motor roller is shown to peripherally frictionally engage the idlr wheel at a Portion of its periphery which is disposed below its axis of rotation and, as best shown in Fig. 1, the spring I! and I8 cooperatively swing the motor M clockwise, as viewed in Fig; 1, to cause the motor roller to effect proper pressure engagement with the idler wheel 20, the spring 11 being interposed between a clip 39 carried by the motor frame and a Portion 30 of the swinging arm 22 which carries the idler wheel, the spring carrying an eye e-e at either end thereof, one said eye being projected through an aperture 39 in the clip 39 and the other said eye being projected through an aperture 30' in the portion 30; said idler wheel and roller being maintained in cooperative pressure engagement.

The tension of the spring l8 secured to an opposite end of the clip 39 by an eye e projected through an aperture 40 thereof andfastened at its opposite end to a lug 43 projecting downwardly from the screw 35, more particularly tends to oppose any tendency of the idler wheel 20 to rollingly travel on the undersurface of the turntable in a direction opposite to the clockwise direction, as viewed in Fig. 1 of the turntable I.

The outer surface of the motor roller I5 is not only tapered but is convexly tapered progressively from the large base portionof its frictional driving surface to its portion of least diameter, in a manner following the teachings of my previously identified co-pending application.

In operation, the turntable is driven in a clockwise direction which requires that the turntable driving idler 20 be rotated in a counterclockwise direction, as illustrated in Fig. 3, wherein the axis of turntable rotation is beyond the illustrated idler wheel. This is achieved by rotation of the motor roller l5, Fig. 3, in a clockwise direction.

At 2:, by dotted lines in Fig. 1, and at m, in Fig. 2, I illustrate a form of an elongated opening in the mounting plate I preferably having an arcuate outermost edge :2 through which the uppermost portion of the idler wheel 20 projects to make driving engagement of the idler wheel tread 24 with the underside 21 of the turntable disc portion I.

The idler wheel would ordinarily transmit to the thereby engaged undersurface of the tumtable a speed equal to that of the idler wheel engaging surface of the roller except for slippage between the idler wheel and said roller and turntable, which occurs .at all operative turntable loads and increasingly as such load becomes heavier. For this reason, the linear speed of the engaged roller surface according to a linear dimension must be greater than the linear speed of the annular turntable surface which is engaged by the idler.

In operation, assuming the roller, idler and turntable are being driven by the motor M, and the turntable is rotating in the clockwise direction, as shown in Fig. l, the idler 20 and roller I5 occupying the positions shown by solid lines when the turntabl is lightly loaded; then, a heavier load imposed upon the idler wheel 20 by virtue of the resultant increased torque has the effect of tending to cause rolling translatory dispiacement of the idler wheel toward the ilustrated dotted line position, and such displacement results in said idler wheel exerting a pushing effort upon the roller 15 to displace it from the solid line position, towards or to the dotted line position, according to the amount of resistance to rotation offered by the frictionally loaded turntable, and the opposition to such displacement offered by the spring l8 and I1.

In such a case, the entire motor M together with it shaft l4 and roller is rotationally deflected on the axis I9 passing through-the axes of tnmnions 8 and 9, against the power of the spring l8. Adjustable rotation of the screw 35 predetermines the proper resistance offered by the motor against rotational deflection.

Shiftingfof the annular zone of engagement of the idler wheel with respect to different longitudlnally disposed portions of the roller surface, is effected by. virtue of the fact that the peripheral engaging surface of said idler and The eifect of such displacement of the idler wheel and motor roller is to shift the annular zone of engagement from that indicated at l5b by the solid lines toward the dotted line indication at I50, as shown by Fig. 1, whereby the idler wheel, upon a light turntable load, engages the driving roller by a roller portionor relatively smaller diameter, indicated at l5b, and under a maximum turntable load, the engagement with the roller portion will be at the zone indicated at l5c, which is of substantially greater diameter.

While various materials may be employed to afford the frictional surfaces of the idler and roller, I prefer that at least the outer surface of the roller be of metallic material and that the tread of the idler be of rubber material.

By the provision of a vertical rotational axis IQ for the motor, I effectively ensure that jars and jolts communicatedto the phonograph mechanism will not be effective to vary the driving pressure as between the outer roller surface and the rubber tread of the idler wheel.

In the embodiment illustrated, the axis of rotation IQ of the roller 15, motor shaft l4 and the rotor of the motor 'M is preferably disposed in a horizontal plane parallel to that of the turntable supporting disc I and located substantially below said disc, and in all operative rotative adjusted position extends in the vertical plane of varying chords of the turntable disc.

The curved outer surface l5d of the roller is convexly so formed that 'when the arm 22 supporting the idler wheel 20 is swung to rotatively' displace the roller about the axis l9, the idler wheel will at'all times engage a longitudinally curved convex portion of the roller surface, in such manner that the axis of curvature of such roller portion will be at that time positioned in the same plane with the medial vertical plane 42 of the idler wheel tread 24.

In each case, the longitudinally convexly curved tapered surface of all sides of the motor roller is generated from an axis in the transverse plane of the base of said tapered roller portion but always applied to the opposite side of the roller from the generated surface. The radial distance of such axis of curvature from the generated curved surface is made proportional to the power with which the adjustment spring [8 opposes the reactive displacement of the motor roller.

In the embodiment illustrated where the radial distance between said generated surface is substantially equal to three and one-third times the diameter of said roller at its said base, tension of the spring l8 may be adjusted by rotation of the screw 35 so as to maintain the desired turn- .table power speed at the heaviest turntable load,

with the idler wheel in engagement with that portion of the roller curved surface which is of greatest diameter. I Responsive to lighter tumtable loads, the idler wheel pressure exerted against the roller is less, and the zone of engagement between idler and roller is shifted towards the end of the roller.

Where the radius of longitudinal curvature of said roller surface is made longer, it will be required to increase the extent of shifting of the zone of engagement of the idler on the roller surface and vice versa, with the roller curvature generated on a shorter radius as great a speed compensating effect may be afforded by a slighter relative movement of the engagement surface of theidler with the longitudinal tapered surface of the motor.

By forming the roller, as illustrated, adjustment of the tension spring will be suilicient to maintain a constant turntable speed within th usual range of turntable loads.

For the solid line positions of Fig. 1, the axis of curvature at 38 of the engaging roller surface W1 is in the projected plane of the dashed line 42, and the lines ll and a indicate different radii of such curvature. Correspondingly for the dotted line position of the roller IS, the idler is in its dash-pot indicated position, and a projection of the medial vertical plane of the idler will include the displaced axis of curvature indicated at 38', the line 4| indicating a radius of such curvature.

For the two illustrated positions of the idler wheel and roller, the axis of the idler wheel is shown as being deflected over an 'angle of approximately 5.3 and, correspondingly, for the same adjustment of parts the motor roller is shown as being displaced over an angle of approximately 13. roller is engaged by the idler wheel at a. point substantially below the axis of the idler whereby pressure exerted between said idler and roller slightly increases the pressure of the idler wheel against the underside l of the turntable disc.

The position of the axis of swinging of the motor M, as indicated in Figs. 1 and 2, is preferably such as to so position said axis that it is disposed centrally of the relatively laterallydisposed massor weight of the motor whereby, preferably, themotor does not tend to exert any substantial amount of lateral pressure against its i supporting bearings, one of which is provided with idler and roller together with the idler supporting arm l5, and motor structure I 0,-are normally resiliently constrained by the spring I! and [8 to resiliently maintain driving pressure engagement between the idler and roller, during all translatory movements of said idler. The spring 18 more particularly exerts a pressure effort to restrain the extent of translatory movement of said system.

The reactive translatory'movement of the idler wheel causes the motor structure including the roller IE to swing about the pivotal axis l9 and two possible positions of the roller are indicated in Fig. 1 respectively by the solid line and dotted line showings of said roller, and the roller is deflected less under light turntable load conditions, and deflected more when a heavier load is imposed upon the turntable.

Although heavy turntable loads would normal- As shown best in Fig. 2, the motor ly involve a slower rateiof turntable rotation, yet because ofj-fithe greater driving ratio, I am able to compensate for'the usual effect of such heavier loads andto maintain the turntable, speed driving surface approximately equal tothe radius constantturntable speed.

of swinging of the medial point 31 of the roller.

I also prefer to provide the common axis for rotation of the turntable for translatory swinging of the idler wheel. The above preferences are dictated by the fact that best results have been secured by following the aforesaid preferences.

Having thus described my invention in a singie embodiment and explaining the structure, mode of operation and results achieved thereby, I am aware that numerous and extensive departures may be made from the structure as illustrated and described but without departing from the operative principle of my invention and its characteristic mode of operation and results.

I claim: a

i; In a friction drive mechanism of the type described for phonograph turntables, .the combination with a mount, a turntable Journalled thereon having a lowermost intra-peripheral, annular and planular smooth turntable surface which is substantially radially spaced from its rotative axis, of an idler wheel disposed in a vertical plane at right angles to a radius of the turntable, said wheel having a peripheral friction tread, an arm journalled to swing in a, horizontal plane below the turntable about the vertical aXiS of said turntable, and said idler wheel journalled on said arm so as to effect frictional engagement between its uppermost wheel tread portion and the said surface, a motor, a driving shaft therefor, aconvexly tapered friction driving roller axially secured on said shaft with its smaller end disposed most remote from the motor, said motor being swingably journalled on said mount with its swinging axis extending substantially vertically, and said roller adapted to be swung into frictional engagement with a portion of said wheel tread surface which is disposed below the horizontal plane of the wheel axis, spring means to yieldably maintain said wheel tread in simultaneous engagement both with said planular turntable surface and with said roller, whereby said motor when energized to rotate said roller is effective to drive said idler and turntable, and said spring means being yieldable whereby upon increased loads applied to said turntable the reactive torque effect thereof upon said wheel will tend to cause said wheelto tractively roll on said turntable zone surface in a direction opposite to the direction of rotation of the turntable and to arcuately deflect said roller and motor shaft about said motor swinging axis, whereby the tractive movement of said'idler wheel is effective to slideably move the power engaging periphery of the wheel tread inwardly along the deflected longitudinal surface of the roller towards the motor to resultantly vary the transmission ratio as between said roller and idler, and means to adjust said spring means to vary the deflection of said roller to substantially 2. In a friction drive mechanism for phono graph turntables of thetypejdescribed, the com bin'ation'with said turntable, a mount upon which I said turntable "is fjof'urnalled for rotation, said turntable comprising a smooth annular horizontal undersurface disposed towardgthe turntable pe- V riphery. a motor carried by'said mount and journalled to arcuately swing horizontally on a vertical axis, a motor shaft extending from an end of said motor, a relatively smooth friction roller secured on the outwardly projecting portion of said'shaft and having at least a longitudinally extending portion of its outer, surface adapted for engagement by said idler'to frictionally drive said idler, an arm disposed below the turntable and journalled for arcuate horizontal movement on said mount substantially inwardly from the turntable periphery, said idler wheel adapted to rotate on a horizontal axis on an outer upwardly disposed portion of the arm on a horizontal axis for hold-- ing the upper tread portion of said idler wheel inv frictional driving engagement with the underside of the turntable, spring means for exerting resilient pressure to maintain the peripheral surface of said idler wheel in engagement with said roller surface, and for resiliently limiting roller displacement by the effect of translatory pushing movements of the idler upon said roller, said idler wheel responsive to different frictional loads imposed upon the turntable, adapted to reactively shift the angular position of its axis in that direction which is opposite to the direction of rotation of the turntable when frictionally drive by id roller driven idler, the idler engaging portion of said roller being of convex conoidal tapered form whereby its remote end portion is of lesser diameter than other portions nearer the motor casing, and said idler being reactively responsive to increased turntable loads to angularly shift its axis of rotation towards said roller so as to deflect said roller against the pressure of said spring means and to shift the zone of engagement from a roller portion of relatively smaller diameter to a roller portion of relatively larger diameter to compensate for turntable speed losses resulting from increased turntable loads and the longitudinal curved outer surface of said roller being so formed that for all operative relative engaging positions led on the mountingplate at a point disposed inwardly of said wheel, a motor swingably journalled at a laterally'diiferent point on said mounting plate having a rotor shaft extending substantially horizontally below the disc, said shaft eerrying at its outer end a tapered roller, the said friction wheel beingiournalled for rotation upon an outer portionjof said arm,'means to continuously hold said wheel and roller in peripheral frictional engagementto drive" said disc, biasing means tending to yieldingly constrain said interengaged wheel and roller to a predetermined normal position, said wheel responsive to the torque erect treatises efl'ect of varying turntable loads to angularly displace said arm towards and from said roller, the interengaging surfaces of said roller and wheel being shiftable during such displacement on intersecting arcs whereby the wheel engages the roller on varying longitudinally disposed portions of the said taperedroller.

4. In a friction drive mechanism of the type described for phonograph turntables wherein a turntable disc is rotatably supported on a tumtable post mounted upon a motor mount for rotation, the combination of a vertically disposed friction wheel in frictional engagement with the underside of said disc, an arm disposed horizontally thereof and rotatably journalled on the mounting plate at a point disposed inwardly of said wheel, a motor swingably journalled at laterally different points on said mounting plate and disposed normal to said disc, said motor having a rotor shaft extending substantially parallel to the turntable, said rotor shaft carrying at its outer end a convexly tapered roller, said roller and shaft being adapted for oscillatory movement about a vertical axis substantially spaced from the swinging axis of the arm, said friction wheel being journalled for rotation upon an outer portion of the said arm, spring means adapted to hold said roller in frictional engagement with said friction wheel to drive said'disc, said wheel being responsive to the torque effect of varying turntable loads to angularly displace said arm towards and from'said roller, the interengaging surfaces of said roller and wheel being shiftable during such displacement on intersecting arcs whereby the wheel engages the roller on varying longitudinally disposed portions of the said tapered roller. I

5. In a friction drive mechanism of the type described for phonograph turntables, wherein a turntable disc is rotatably supported on a turntable post mounted upon a mounting plate for rotation, the combination of a vertically disposed friction wheel in frictional engagement with the underside of said disc, an arm rotatably journalled on the mounting plate at a point disposed inwardly of said wheel, a, motor swingably journalled at a laterally different point on said mounting plate having a rotor shaft extending substantially horizontally below said disc, said shaft carrying at its outer end a convexly tapered roller, the said friction wheel being journalled for rotation upon an outer portion of said arm, means to continuously hold said wheel and roller in peripheral frictional engagement to drive said disc, biasing means tending to yieldably constrain said interengaged wheel and roller to. a predetermined normal position, said wheel responsive to the torque effect of relatively heavy turntable loads to angularly shift its axis of rotation towards said roller so as to deflect said roller against the pressure of the biasing means tend to shift the zone of entable post mounted upon a motor mount for rotation, the combination of a vertically disposed friction wheel in frictionalengagement with the underside of said disc, said plate having an aperture therein and said friction wheel projected through said aperture, an arm "disposed horizontally thereof and rotatably journalled on the mounting plate at a point disposed inwardly of said wheel, a motor swingably journalled at laterally different points on said mounting plate and disposed normal to said disc, said motor having a rotor shaft extending substantially parallel l roller in frictional engagement with said fr ction l gagement from a roller portion of relatively 7 larger diameter to compensate for turntable speed losses resulting from said increased turntable loads.

6, In a friction drive mechanism of the type described for phonograph turntables wherein a turntable disc is rotatably supported on a turnto the turntable, said roto shaft carrying at its outer end a convexly taperedroller, said r ller and shaft-being adapted for oscillatory movement about a vertical axis substantially spaced from the swinging axis of the arm, said friction wheel being journalled for rotation upon a depending portion of the said arm, means maintaining said wheel in pressure engagementfwith said disc, spring means adapted to hold, said wheel to drive said disc, said wheel being responsive to the torque effect of varying turntable loads to angularly displace said arm towards andlfrom said roller, the interengaging surfaces of said roller and wheel being shiftable during such displacement on intersecting arcs whereby the wheel engages the roller on varying longitudinally disposed portions of the said tapered roller, i

'7. In a friction drive mechanism of th type described for phonograph turntables whe ein a turntable disc is rotatably supported on a turntable post mounted upon a motor mount for rotation, the combination of a vertically disposed friction wheel in frictional engagement with the underside of said disc, an arm disposedhorizontally thereof and rotatably journalled on the mounting plate at a point disposed inwardly of said wheel, a motor swingably journalled at laterally different points on said mounting plate and disposed normal to said disc, said motor having a rotor shaft extending substantially parallel to the turntable, said rotor shaft carrying at its outer end a convexly tapered roller, said roller and shaft being adapted for oscillatory movement about the axis of swinging of the motor disposed centrally of the mas of the motor, said friction-wheel being journalled for rotation upon an outer portion of the said arm, spring means adapted to hold said roller in frictional engagement with said friction wheel to drive said disc, said wheel being responsive to the torque effect of varying turntable loads to angularly displace said arms towards and from said roller, the interengaging surfaces of said roller and wheel being shiftable during such displacement on intersecting. arcs whereby the wheel engages the roller on varying longitudinally disposed portions of the said tapered roller.

BLAKE W. CARRINGTON.

REFERENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENTS Number Name Date 2,312,798 Carrington' Mar. 2, 1943 

